1. Field of the Invention
The present invention relates to an improved seat-belt-type passive restraint for a vehicle seat which is so designed as to be able to secure the safety of an occupant when shocks are given to the occupant due to the collision of the vehicle or the like.
2. Description of the Prior Art
Conventionally, a passive restraint of this type is constructed such that a belt retractor is mounted on the side of a vehicle body. In such passive restraint, when an occupant adjusts the position of his or her seat while the occupant is restrained, his or her belt wearing attitude is changed. Thus, it is necessary to adjust the length of a seat belt each time the position of the seat is adjusted. Also, when a seat belt of a relatively larger length is employed, the seat belt itself may be stretched, resulting in the deterioration of the restraint performance of such passive restraint for its wearer when a collision occurs.
In view of these circumstances, many improved passive restraints have been proposed in which a belt retractor is mounted on the side of a seat, i.e., within a cushion frame so that even when the occupant adjusts the position of the seat while he or she is restrained the restraining condition of the seat belt will never be altered.
In such passive restraint of the last-mentioned type, however, there are still some problems which arise when the retractor is mounted within the cushion frame. Specifically, if the belt retractor is located on the lower surface side of a sitting portion of the seat or in the lower portion of the cushion frame which is opposed to an input portion for the seat belt, the belt retractor may be abutted against the lower surface of a seat pad forming the sitting portion of the seat, or the seat belt runs across and is abutted against the lower surface of the seat pad. This gives the occupant a strange feeling while seated and also provides an obstacle to the correct operation of the seat belt. Also, the seat belt itself is brought into direct contact with the cushion frame so that it may be contaminated or broken. Further, since it is necessary to form a bore for insertion of the seat belt in the cushion frame, the strength of the cushion frame is decreased accordingly. Such decreased strength must be compensated by some reinforcement means and this reinforcement means results in the increased weight of the cushion frame itself.
In addition, when assembling such passive restraint, after the belt retractor is fixed to the cushion frame, the seat belt must be guided out externally by means of the insertion bore formed in the side surface of the cushion frame and, in particular, it is difficult to insert through the bore a large-sized buckle mounted at the free end of the seat belt. In other words, such passive restraint is disadvantageous in that it takes much time and labor in assembling.